1. Field of the Invention
This invention relates to the nonrecovery coking of coal, and more particularly to an improved coke oven battery for and process of nonrecovery coking of coal.
2. Description of the Prior Art
The practice of producing metallurgical coke by a nonrecovery coking process was for many years all but abandoned in favor of the byproduct coking process in which the coke gas and other chemicals were recovered and/or refined for further use. The high cost of constructing and operating such byproduct coking plants has resulted in renewed interest in the nonrecovery process in recent years, however, and substantial improvements have been made both in the operating efficiency and pollution control of nonrecovery ovens. Examples of modern high speed sole flue type nonrecovery coke ovens now in operation in the United States are disclosed in Thompson U.S. Pat. Nos. 4,287,024 and 4,344,820, and the present invention is an improvement over the coke apparatus and process disclosed in these patents.
Difficulty has been encountered in consistently obtaining a uniform coking rate throughout all the ovens in a battery constructed in accordance with the Thompson patents described above. Such ovens may have a coking chamber of up to fifty (50) feet in length and twelve (12) feet in width, and may be filled to a depth of up to five (5) feet or more with green coal at the beginning of a forty-eight (48) hour coking cycle. Normally eight (8) or more adjacent ovens are connected through a common combustion tunnel to a single stack, and no means other than varying the amount of combustion air admitted through inlets in the oven doors, the sole flues, and the common tunnel, are provided for varying the draft to the respective ovens. Since the uptakes leading from one of the two flue systems under each of two adjacent ovens are connected through a common connector to the combustion tunnel, adjusting the combustion air to one oven necessarily effected the draft to the adjacent ovens. Also, the downcomers are located outboard of the uptakes, making it possible for combustion air to be short circuited through the door inlets to the closest downcomer so that insufficient air reached the center portion of the oven crown, thereby reducing the burning of gases and the coking rate in this area. In contrast, excess combustion air in the area adjacent the door inlets can result in excess burning in this portion of the oven with the consequent waste of product. Further in the event of incomplete coking of the charge near the center of the oven, excess emissions may be released to the atmosphere upon pushing of the incandescent coke at the end of the cycle. It is, therefore, a primary object of the present invention to provide an improved nonrecovery coking battery and method of its operation for the high speed coking of coal at a more uniform coking rate throughout the ovens in the battery.
Another object is to provide such a coking installation including improved means for controlling and regulating the draft supplied to the individual coking ovens in a battery of ovens connected to a common stack.
Another object is to provide such an installation and a method of its operation, which enables an increased yield of high quality coke from a charge of coal.